Method and apparatus for preservation of perishable foodstuffs



Dec. 5, 1.939. D. vw. GRlswoLD METHOD AND APPARATUS FOR PRESERVATION 0FPERISHABLE FOODSTUFFS Filed Aprii- 2o, 1957 '2 Sheets-Sheet l .IE IlDONALD \A/. Gmawom l NTOR ATTORNEY 5, D. w. GRlswoLD 2,182,556METHOD'AND APPARATUS FOR PRESERVATIONOF PERISHABLE FOODSTUFFS I FiledApril 20, 1937 2 Sheets-Sheet, 2

Y vDommcls GmswoLp E TOR AITORN EY Patented Dec. 5, 1939 Ferca :METHODAND APPARATUS FR PRESER- VATION OF PERISHABLE FOODSTUFFS Donald W.Griswold, Bridgeton, N. J.

Application April 20, 1937, Serial No. 137,950

8 Claims.

This invention relates to a method and apparatus for the preservation ofperishable foodstuffs, such as, fresh vegetables, berries,.fruit, etcetera, and more particularly to the preserving of such foodstuffs byfreezing.

With the present type of apparatus for preserving foodstuffs byfreezing, the foodstuffs are frozen ln packages or blocks either in whatis known as the cabinet type of freezing apparatus or on the endlessconveyor type.l The use of these types of freezing apparatus and thefreezing of the foodstuffs in packages, pans or in bulk, requiresconsiderable labor, particularly in thecabinet type of freezingapparatus, and in all instances freezing of the foodstuffs in blocks orpackages of predetermined sizes. The freezing of the foodstuffs inblocks or packages not only requires a relatively long time tothoroughly freeze them through to the center of vthe block or package,but requires that they be sold or used in definite predeterminedquantities. Frequently a housewife does not require an entire block offoodstuffs for her needs; then she must cut the block to obtain thedesired quantity. The freezing of the foodstuffs in blocks or packagesalso requires a relatively long time to thaw them out in readiness forcooking or eating. If vthe blocks are broken up to facilitate thawingthis crushes and mutilates some of the individual pieces or units and isparticularly undesirable in connection with berries and fruits which areused as dessert and are desired to appear attractive when placed on thetable. l

An object of the present invention is to provide a new and novel methodand apparatus for= freezing foodstus by means of which the units orpieces of food are frozen individually, that is, each pea; lima bean,leaf of spinach, cob of corn, string bean, raspberry,` strawberry, etcetera, is

o individually frozen in a continuous quick freezing method whichmaterially cuts down the time required for freezing, reduces to aminimum manual labor required in handling the foodstuifs, and permitsthe frozen foodstuffs to be dispensed and used in any desired quantity.

The present method and apparatus provides that each and every individualpiece or portion has been done heretofore with approved com-l vantages,and savings in initial cost of equipment mercial apparatus now in use.By the quick freezing of the foodstus all the natural avor and qualityare retained and preserved, because the cellular construction of thefoodstuffs remain unbroken and unchanged.

Another object of the present invention is the provision of a foodfreezing apparatus which will be self-'defrosting, that is, it willprevent thev accumulation of frost on the heat-exchange surfaces thereofand consequently the continuous action of the apparatus is constant andunchanging, and also the apparatus will produce a product of betterquality than can be produced by the present approved type of apparatusand at a .lower cost. 5

A further object of the present invention is the provision of anapparatus for freezing foodstuffs which is designed and constructed topermit the use of volatile refrigerants as the refrigerating medium,with its consequent many adand in subsequent operating costs. Theapparatus is constructed so as to prevent any possibility of thefoodstuffs absorbing odors or having its flavor impaired by the use of avolatilev refrigerant.

The present method and apparatus of continuous and individual freezingof foodstuffs will synchronize with the present approved methods ofcontinuous flow of vegetables or fruits through the lines or apparatusemployed in the preparation of fruits and vegetables for canning, andwill eliminate delays caused by manual handling, or holding byaccumulation of such foodstuffs after preparation which often results inspoilage and as is occasioned in the use of the present package cr bulkfreezing apparatus.

With these and other objects in view, as may appear from theaccompanying specification, the invention consists of various featuresof construction a`nd combination of parts, which 'will be lirstdescribed in connection with the accompanying drawings, showing a methodand apparatus for preservation of perishable foodstuffs of the preferredform embodying the invention, and the features forming the inventionwill be specifically pointed out in the claims.

In the drawings:

Figure 1 is a side elevation of. a food-preserving apparatus constructedin accordance with the present invention and having parts thereof brokenaway.

Figure 2 is a vertical section taken on the line 2-2 of Figure 1. l

Figure 3 is a longitudinal section through the 55 carrying tubes.

apparatus taken approximately on the line 3-3 of Figure 2.

Figure 4 is a detail section on the line 4-4 of Figure 3.

Figure 5 is a longitudinal section through a modified form of the unit.

4Figure 6 is a cross section on the line 6-6 of Figure 5.

Referring more particularly to the drawings, the type of apparatus forpreserving foodstuffs by freezing, shown in Figures 1 to 4 inclusive, isa type particularly adapted for the use of a volatile refrigerant as therefrigerant medium.

In the carrying out of the present method of freezing foodstuffs thefoodstuffs are first prepared in the usual manner and required methodand after such preparation are fed in any suitable manner to the inletor receiving-hopper I of the freezing apparatus.

The freezing apparatus comprises a plurality of pipes or tubes 2 whichare arranged, preferably in superposed relation, or may be arranged inany suitable series relationvto receive the foodstuffs, one from thepreceding one. The tubes 2 have their major portions encased inrefrigerantforming housings or tubes 3 which are spaced from thefood-carrying tubes 2 to provide refrigerant-containing chambers 4 aboutthe food- Refrigerant of any suitable type, preferably volatilerefrigerant is delivered to the respective refrigerant chambers 4 byasuitable structure whichwill insure the delivery of the proper amountlof refrigerant to thev refrigeration or evaporator chambers 4 withoutythe need of a refrigerant circulating pump and its necessary appendages.Also the refrigerant distributing means is self-regulating.

The refrigerant distributing structure includes a distributor I which isshown in the form of a vertical stand-pipe and it has a plurality ofpartitions therein which correspond to the various vertical tiers of theevaporator chambers 4. The partitions are located slightly below thelowermost part of the respective tier. of evaporator chambers and formpockets in the distributor III which are individual to each of theevaporator chambers. A volatile refrigerant is supplied from anysuitable source (not shown) through a supply pipe vI2 to the accumulatorI4. The accumulator I4 is mounted at the top of the distributor I0 andopens thereinto so that the liquid refrigerant delivered to theaccumulator I4 may pass down- Wardlyinto the distributor I0.

Each of the pockets in the distributor I0 formed by the partitions isconnected by suitable suplply pipes l to the respective evaporator cham-Pipes I6 extend through the partitions II, extending a predetermineddistance above and below the partitions and form the only means ofrefrigerant delivery communication between the respective pockets.necessary for the liquid refrigerant to rise above the tops of theseoverflow pipes before any liquid refrigerant will be supplied to thepocket next' therebelow. q The overflow pipes I6 project upwardly intothepockets a predetermined distance for regulating the height of theliquid refrigerant in the evaporator chambers 4. e

The overflow pipes I6 are of such height that there will always be lefta gas pocket as indicated at I 'I in the uppermost portions of theevaporator chambers 4, and these gas pockets are connected by pipes I8to the respective pockets in the disneeds of the apparatus.

It will, therefore, be.

tributor above the tops of the overflow pipes I 6. The evaporated liquidrefrigerant thus passes from the evaporator sections or chambers 4through the pipes I8 into the distributor pockets and passes from onedistributor pocket, through a gas outlet or tube I9 into the next pocketthereabove and thence onwardly through the series of pockets in theaccumulator I4. Any condensation of the gases or evaporated liquidrefrigerant will pass or fall downwardly into the respective distributorpockets and be recirculated. A suitable gas take-olf as indicated at 20may be provided. The supply of liquid refrigerant to the accumulator I4and consequently to the distributor I0 is controlled by the level of theliquid refrigerant in the lowermost tier of evaporating chambers 4 by afloat mechanism 2|, of any approved type, which in turn controls thevalve 22. The float mechanism 2| includes the tank or condenser 23 whichis connected by the pipe 24 to the bottom of the distributor i0 and isplaced so that the level of the liquid refrigerant within the tank 23will be level with the levelof liquid refrigerant in the evaporatorchamber 4 of the lowermost of the freezing or evaporator units. Sincethe evaporator chamber 4 in the lowermost unit is the last to receivethe liquid refrigerant and the iioat structure 2| is arranged to openthe Valve 22 until such time as the level of the liquid refrigerant inthe lowermost evaporator chamber 4 reaches the desired height, thechilling apparatus will bevselfregulated and the quantity of liquidrefrigerant delivered thereto will be cont olled by the actual Thefoodstuffs entering the tubes or pipes 2 are 'picked up by thespiral-blade conveyor 30 which feeds or conveys the individual particlesor units of food through the tubes 2. The spiral conveyor structures 30may be rotated at any desired speed from any suitable power source (notshown) through the medium of sprockets 3| and the spiral blade-carryingshafts 32. The speed of the feeding of the particles of food through thetubes is regulated in accordance with the freezing action orheat-exchange action of the volatile refrigerant in the variousevaporating or refrigerant chambers 4. v

The shaft 32 may have aplurality of agitating paddles orstirring blades32 thereon at spaced intervals along its length lfor stirring oragitating the foodstuffs as they are fedthrough the tube 2. If it is sodesired the conveyor structure may itself be so constructed inaccordance with standard conveyor practice to agitate or'stir the food-1 stuffs during their passage through the tube 2. y The conveyors andagitating paddles Will roll and agitate the various particles lof foodduring leak out of the tubes willpassA through the tubes and out thefinal outlet 34 with the frozen foodstuffs.

In Figures 1 and 2 of the drawings, a plurality of the freezing unitsare shown, connected in series and the food particles or units passlongitudinally through one freezing unit from its inlet end to itsoutlet end, and drop by gravity through connections 33 to the inlet ofthe next unit. being delivered from the unit end of the final freezing uunit Ythrough a discharge 3l, into any suitable type of containers orpackaging means.

A It is to be understood, that if it is desired only one freezing unitmay be employed which is of suiiicient length that the proper freezingof. the foodstuffs may be obtained by their vpassage through this singlefreezingunit.

The inlet ends of the food-receiving tubes 2 are provided with aplurality of openings 35 through which precooled air is admitted to thetubes from any suitable source (not shown), and by any suitable meanssuch as 'the conduit 36. Thus the food particles or units are subjectedto a. blast of uniform precooling air when they first enter the freezingapparatus and are subsequently subjected to blasts of air at regularintervals through their continued passage through the series of freezingor heatexchange units.

The spiral-blade screw conveyors, rotating at a relatively slow speedwill gently and continuously move the foodstuffs through the freezing orheat-exchange unit and every individual piece or portion of a fruit orvegetable will be subjected to uniform application of heat exchange orfreezing action, and this together with the application of the precooledair to the foodstuffs 'will insure rapid freezing and the maintenance ofthe full natural flavor and quality of the foodstuffs, be-

cause the cellular construction thereof will -re.

main unbroken and unchanged.

The spiral-blade screw conveyors just touch or engage the inner walls ofthe tubes or pipes 2 so that they will form scrapers and prevent theaccumulation of frost on the walls of the tube which causes impairmentof the heat-exchange properties of the apparatus. In other words, thefreezing or heat-exchange units will be self-defrosting and the foodstuspassing therethrough will always be subjected to uniform freezing orheat-exchange conditions.

In Figures and 6 of the drawings, a modied form of the freezing orheat-exchange unit is shown, this form being particularly adapted foruse in connection with a non-volatile refrigerant.

The modified form of the invention comprises a foot-receiving tube lliinto which the particles of food are delivered through a suitable inlethopper di and in which is positioned spiral-blade screw type conveyord2, similar to the .conveyor shown in Figures 1 to 3 inclusive of thedrawings. The spiral blade d3 of the conveyor 42 is carried by asuitable operatingshaft 4 which is rotated in any suitable manner, andthe spiral blade 53 scrapes the inner wall of the tube l0 to prevent theaccumulation of frost thereon.

- The shaft 46, however, is hollow and is provided with a plurality ofradial perforations 65 at longitudinally spaced points therein. Thehollow shaft Il has connection with a supply source (not shown) ofprecooled air under a predetermined pressure such as through aconnection shown at 46. Therefore, during the passage of the foodstuffsthrough the tube 40 they will be constantly subjected to blasts ofprecooled air.

The foodnuifs may also be subjected to the blasts of precooled airthrough the openings 41 in the same manner in which the precooled air issupplied to the tubes 2.

The tube di! has its maior portion surrounded by a refrigerating chamber48 which. has an inlet B9 for non-volatile refrigerant at one endthereof, and an outlet 50 for the refrigerant at the other end.longitudinally extending baflies 5i are placed in the refrigerantchamber 48 and they are disposed staggeredly, that is, they terminateshort of the endsof the chamber at opposite ends thereof as shownat 52in Figure 5 of the drawings, so as tocompel the refrigerant which ispumped through the chamber 46 to pass therethrough in a sinuous ormulti-pass path to enhance the heat-exchange action thereof and.con'sequently increase the freezing action of the foodstuffs passing throughthe food tube 40. The

discharge. of -the frozen foods is preferably byv gravity through adischarge tube shown at 53. If it is so desired the hollow shaftarrangement shown in Figures 5v and 6 of the drawings may be used in thetype of refrigerating unit adapted for use of a volatile refrigerant,without -departing from the spirit of the present invention, and thefreezing units adapted for use of a nonvolatile refrigerant may beconnected in series to provide a multi-unit apparatus, in any desired orpreferred arrangement, or they may beused singly, without departing fromthe spirit of the present invention, and it isalso to be understood thatthe invention is not to be limited to the particular apparatusillustrated for the circulaion of the volatile refrigerant but thatother pracical structures may be employed. In all of the drawings andhereinabove the con veyors have'been referred to as spiral-blade screwtype propellers with or without agitating paddles,

but it is to be understood that the invention is` tubes may be usedwithout departing from the spirit of the present invention. v

Also it may be desirable to employ various gases instead of air in thefreezing of the foodstuffs, and it is to be understood that such usefails within the scope of the present invention.

It will be understood that the inventionl is not to be limited to thespecific construction or arrangement of parts shown but that they may bewidely modified within the invention dened by the claims.

.What is claimed is: i

1. In an apparatus for freezing foodstuffs, a plurality of heat-exchangeunits arranged in series, each of said units comprising a food-receiving tube and a conveyor therein, the discharge end of each tube beingconnected to the ventrance end ofthe succeeding tube in the series andarranged whereby the foodstuffsv will fall by gravity from one tube tothe succeeding tube,

refrigerant chambers surrounding the maior portions of said tubes, saidtubes provided with openings to admit precooled air thereinto, and meansfor conveying precooled air to saidopenings.

2.-In an apparatus for freezing foodstuffs, a food-receiving tube, aconveyor in said tube for feeding the foodstuffs in continuous motionthrough the tube and agitating it during its pas` sage, a refrigerantchamber surrounding the major portion of said tube, a rotating shaft forsaid conveyor, said shaft being hollow and provided with lperforationsto permit ejection of air from the shaft into the tube.

3. The method of freezing foodstuffs which consists in substantiallycontinuously moving individual pieces of foodstuff in heat exchangerelationship with a liquid refrigerating medium for freezing the piecesof foodstuff individually, and

subjecting 'the pieces of foodstuff to a blast of cooled air at thestart of their movement in heat exchange relationship with therefrigerating medium.. 'f I 4. The method of freezing foodstuffs whichconsists in substantially continuously moving individual pieces of fruitor vegetables in heat exchange relationship with a refrigerating mediumfor freezing the pieces of fruit or vegetables individually, subjectingthe pieces of fruit or vegetables to a blast of cooled air at the startof their movement in heat exchange relationship with the refrigerantmedium to quickly form a frozen outer crust on the pieces of fruit orvegetables, and agitating the pieces of fruit or vegetables to cause atumbling movement thereof during their movement in heat exchangerelationship with said refrigerating medium.

5. The method of freezing foodstuffs which consists in substantiallycontinuously moving individual pieces of fruit or vegetables in heatexchange relationship with a refrigerating medium for freezing thepieces of fruit or vegetables individually, subjecting the pieces offruit or vegetables to a blast of cooled air at the start of theirmovement in heat exchange relationship with the refrigerant medium toquickly form a frozen outer crust on the pieces of fruit or vegetables,agitating the pieces. of fruit or vegetables to cause a tumblingmovement thereof during their movement in heat exchange relationshipwith said refrigerating medium, and further subjecting the pieces offruit or vegetables to successive blasts of precooled air during theirmovement in heat exchange relationship with said refrigerating medium.

6. In an apparatus for freezing foodstuffs, a food receiving tube, aconveyor in said tube for feeding foodstuffs in continuous motionthrough the tube, means for delivering p recooled air to said foodstuffat the entrance end of the tube, and agitators in said tube for engagingfoodstus therein independently cause a tumbling agitated movement of thefoodstuis out of the normal path of the foodstuffs caused by saidconveyor during passage to the tube. Y

7. In an apparatus for freezing foodstuffs, a food receiving tube, a.conveyor in said tube for feeding foodstuffs in continuous motionthrough the tube, means for delivering precooled air to the entrance endof the tube, and means for y delivering precooled air into said tube atspaced points along its length.

8. In an apparatus for freezing foodstuffs, a food receiving tube, aconveyor in said tube for feeding foodstuffs in continuous motionthrough the tube, a refrigerant chamber surrounding the major portion ofsaid tube, la rotating shaft for of said conveyor to f said conveyor,foodstuff agitating paddles on said shaft arranged to break up thenormal passage of the foodstuffs as they are conveyed by said conveyer,and means for delivering precooled air to one end of said tube and intothe tube in a direction transversely ofthe direction of entrance of thefoodstuffs into the tube.

DONALD W. G RISWOLD.

